Purification and sequencing of a rat intestinal 22 amino acid C-terminal CCK fragment

• Published in: Peptides (New York, N.Y. : 1980) Vol. 5; no. 6; p. 1203
• Main Authors: Eng, J, Du, B H, Pan, Y C, Chang, M, Hulmes, J D, Yalow, R S
• Format: Journal Article
• Language: English
• Published: United States 01-11-1984
• Subjects: Amino Acid Sequence; Animals; Cholecystokinin - isolation & purification; Intestines - analysis; Peptide Fragments - isolation & purification; Protein Processing, Post-Translational; Rats; Sincalide - isolation & purification
• ISSN: 0196-9781
• DOI: 10.1016/0196-9781(84)90188-8

Fractionation on Sephadex G50 gel of methanol extracts of rat intestine revealed two molecular forms of cholecystokinin (CCK) of about equal immunopotency: one form has an elution volume between CCK33 and CCK12; the other elutes in the salt region as does authentic CCK8. Purification and sequencing have demonstrated that the smaller molecular form is CCK8 with a sequence identical to the pork and sheep CCK8's that had previously been sequenced. Purification and sequencing of the larger molecular form reveals that it is a 22 amino acid C-terminal CCK fragment identical with pig CCK22 except that glycine instead of serine is present at the nineteenth residue from the C-terminus. This sequence is consistent with that predicted by cloned cDNA encoding preprocholecystokinin from a rat medullary thyroid carcinoma. CCK22 has not previously been reported to be a prominent molecular form in either pig or dog intestines.